The methodology and instrumentation have been developed for quantitatively measuring the resistance to passive joint movement at constant angular velocities. The objective of the proposed study is to establish the scientific merit of such measurements as a measure of spasticity for a specific population of cerebral palsied individuals. Biomechanical measurements of the torque resisting passive movement of the knee and ankle joints will be obtained at three constant angular velocities. Static torque measurements will also be obtained at four joint positions. The relationships of resisting torque to angular velocity and static torque to position will be examined and compared to a normal population. The effects of test duration, test sequence, and repetitive testing will be determined. Successful quantitative characterization of spasticity can provide the design for a brief clinical test for spasticity which can be implemented without the need for expensive apparatus or highly sophisticated instrumentation.